Hi there, after looking at your posts i'm thinking you're just looking for an answer because the tests you've had so far unfortunately havent come up with an abnormality and you're left without an answer for what your dealing with.....
If you've come across symptoms associated with MS whilst googling your symptoms and are just testing the water trying to find something that sticks, then please consider googling doesn't explain what MS symptoms can or can't do and 'breast swelling' would generally be a red flag pointing away from a neurological condition like MS as a causation.
In Feb 2020 you posted (indicating you first noticed your left breast swelling started around october/november 2019)
"Changed birth control brand about 3 months ago. Feel like my hormones are off. Went to dr last week for bad cyst pain left side had ultrasound showed nothing. Also noticed left breast swelling but thought it was due to oulling my chest muscles from falling back on a ladder. Now I noticed my left nipple has a red enlarged apot that is itchy and feels tender. I had a small scab that had a white powder underneath. My wants a diagnostic mammogram which i disagree with. How do i get just an ultrasound? Or give it time to heel?"
I would suggest if the more common breast and hormonal related medical issues have all been ruled out, you could speak to your GP about if what your experiencing could be a nerve related medical issue because pain, burning and itching are all symptoms associated with nerve issues, more commonly the peripheral nervous system but keep in mind an ultrasound won't help diagnose most medical conditions associated with the peripheral nervous system so you'll probably need tests like blood work up, spinal MIR, ct and or xray etc etc
Hope that helps a little..........JJ